Psychotic disorders such as schizophrenia and mood disorders such as major depression and bipolar disorder are a major public health problem, affecting a significant portion of the adult population of the United States each year. While it has been hypothesized that mental disorders, including psychotic disorders such as schizophrenia as well as mood disorders such as major depression and bipolar disorder have genetic roots, little progress has been made in identifying gene sequences and gene products that play a role in causing these disorders, as is true for many diseases with a complex genetic origin (see, e.g., Burmeister, Biol. Psychiatry 45:522-532 (1999)). Relying on the discovery that certain genes expressed in particular brain pathways and regions are likely involved in the development of mental disorders, the present invention provides methods for diagnosis and treatment of mental disorders such as schizophrenia, as well as methods for identifying compounds effective in treating mental disorders.